When Briana Clarke heard popping sounds on a Seattle college campus Thursday, she thought the source must be something innocent - bursting balloons. Then she saw a classmate running frantically, saying someone had been shot.

A gunman had opened fire at Seattle Pacific University, killing one person and wounding two more before he was tackled by a student security guard, Seattle police said.

The gunman was reloading a shotgun when the tackler, working as a building monitor, used pepper spray and knocked him down, police Capt. Chris Fowler told reporters.

"Once on the ground, other students jumped on top of them and subdued the shooter," he said.

The suspect, 26-year-old Aaron Ybarra, is not a student at the school, police said.

They say they think he acted alone, but the investigation is continuing. Police did not disclose a motive.

A day after a Murrysville, Pennsylvania, teen allegedly rampaged through his high school's hallways, stabbing wildly with two kitchen knives, the first hints of a possible motive began to emerge.

The attorney for 16-year-old Alex Hribal raised the specter that his client may have been bullied, telling CNN affiliate WTAE in Pittsburgh on Thursday that it looks like some kind of "bullying event" may have played a role.

"I think a lot of things have happened. I don't want to comment specifically, but I think there are some things that occurred that led to where we are today," Patrick Thomassey said.

But an FBI official, familiar with the investigation, discounted bullying as a motive.

"He was disaffected but not bullied," the official said on condition of anonymity.

Hribal, a sophomore, was charged as an adult and faces four counts of attempted homicide and 21 counts of aggravated assault in connection with Wednesday's attack at Franklin Regional Senior High School that left 20 teens and one adult wounded.

Some classmates at the school describe Hribal as having few friends and being quiet but also as a "really nice kid," a description that contradicts the image of a knife-wielding teen offered by authorities.

With each passing day, the toll grows from a mountain that moved, a massive landslide that swallowed houses and trailers in Washington's Cascade Mountains.

At least 16 bodies have been recovered, another eight bodies have been located but not recovered. That toll is only expected to grow as searchers dig through a mountain of mud and debris to try to find the people who called the towns of Oso and Darrington home.

Some were from the area, and others were drawn by the remote beauty of the rugged Cascade Mountains.

They were neighbors and, in some cases, friends.

Among them was a Navy commander with a love of the mountains and a retired couple living out their twilight years by spending time with their children and grandchildren. Then there was a 20-something and the man she loved, who were planning a wedding at the woman's family home.

Yahoo is slamming as "completely unacceptable" a British agency's alleged collection of digital images while eavesdropping on webcam chats, a spokesperson for the Internet search engine said Thursday.

And Yahoo says if the electronic spying took place, the online mainstay had nothing to do with it.

"We are not aware nor would we condone this reported activity," the spokesperson said following a published report by the UK-based Guardian newspaper that Britain's Government Communications Headquarters, known as GCHQ, spied on people using Yahoo webcam chats, whether or not those users were investigative targets.

According to the Guardian report, which cites documents leaked by former National Security Agency intelligence contractor Edward Snowden, the GCHQ collected the images under a program known as "Optic Nerve."

The documents show, according to the Guardian, that the GCHQ - with reported aid from the U.S. National Security Agency - intercepted and stored the webcam images of millions of Internet users.

If the report is true, it is "completely unacceptable," the Yahoo spokesperson said.

The mass collection of digital images of Yahoo users began because GCHQ targets were known to use the search engine's webcam, the documents said, according to the Guardian.

During a six-month stretch in 2008, the GCHQ allegedly collected images from webcam chats from 1.8 million Yahoo users globally, the newspaper reported.

The still images were allegedly collected at five`-minute intervals during the chats. One document, according to the Guardian, compared the collection of digital images to that of a massive digital police mugshot book.

GCHQ declined to speak to the allegations, citing a longstanding policy that it does not comment on intelligence matters.

"Furthermore, all of GCHQ's work is carried out in accordance with a strict legal and policy framework, which ensures that our activities are authorized, necessary and proportionate, and that there is rigorous oversight," according to a statement released by the agency's press office.

GCHQ is not bound by the same rules that seek to limit the NSA collection of information on its citizens. However, according to the Guardian, there are additional legal authorizations required before the agency can search for data on suspected targets in believed to be in Britain.

According to the documents, there was no mechanism in place to block the collection of data on U.S. and U.K. citizens, the Guardian reported.

The leaked documents also allegedly provided insight into how the spy agency grappled with how to deal with the pornography it encountered in webcam chats.

"Unfortunately, it would appear that a surprising number of people use webcam conversations to show intimate part of their body to the other person," one document said, according to the Guardian.

The GCHQ estimated that up to 11% of the digital images it collected from the webcam chats were explicit, the Guardian reported, citing the leaked documents.

As a result, the GCHQ allegedly warned its analysts that some of the material collected may be offensive.

"User who feel uncomfortable about such material are advised not to open them," one document said, according to the Guardian.